1. Field of the Invention
The present invention generally relates to gripping devices and, more particularly, to self-locking gripping device which can adjust itself to a variety of objects to be torqued, compressively, grasp the object then transfer torque, in either direction. This invention is ideally suitable to be used in the area of torque tools, such as rachet tools and tool chucks in a variety of applications, such as in conjunction with various size drill bits, lathe applications and the like.
There are many examples where applications of torque is necessary. For example, an object to be lathed is set into a lathe chuck, the chuck is then tighten and then torque is applied. After the torquing operation, the object is then released from the chuck and the lathe is available for the next object to be torqued. Other popular examples include drilling: a drill bit is set into a drill chuck, the drill chuck is then tightened to firmly grasp the drill bit and then torque is applied to the bit. After the torquing operation, the drill bit is removed by releasing the drill bit to make the drill bit available for the next size bit. Another very popular torque application is in the field of bolt torquing.
2. Brief Description of the Prior Art
A need has existed for a tool which is durable and allows for the quick and effective gripping and torquing of objects, such as bolt heads of any size. An examination of prior attempts to fill the need demonstrate the usefulness, novelty, and non-obviousness of the present invention.
In the field of bolt torquing: a common device known to many is the traditional standard set of sockets. A series of sockets of varying, standard sizes is provided to interact with a standard size driving ratchet, a handle with a standard size rachet prong, usually having a square cross-section with locking ball. The standard socket sets are used by matching a particular size socket to be used in conjunction with a particular size bolt head, as each socket will fit a bolt of only a particular size head. Moreover, because bolts are commonly either metric sized or English sized, there is the need to have a complete set of both metric and English sockets to be able to torque any bolt. Such sets are cumbersome as one must often try a variety of sockets before finding the right sized socket for the job. Additionally, the socket sets are bothersome to store, the sockets in the different standard sets often are misplaced, and require care to maintain in an orderly fashion; furthermore, the particular sockets are easily lost or misplaced. Because of standardization, standard size sockets are little or no use for an off standard sized bolt caused by bolts made of poor quality, either in size or in material or by changes in bolt sizes due to re-standardization. Further, standard size sockets may not work with bolt heads which are worn or improperly sized. The standard set of sockets in this case would have a socket either too small to fit onto the bolt head or too large to be able to grasp the bolt head.
Several adjustable socket designs attempt to address these problems. For instance, several adjustable socket designs often require that one use both hands to secure their socket tool onto a bolt head before it can interface the tool with a ratchet. These sockets have no means to automatically adapt to the bolt head nor do they have any means to insure that the jaws remain parallel to impart torque. Other designs rely on a power screw configuration to create adaptation and apply torque. However, such designs often require the tool to travel through several rotations and these designs are unidirectional. Still other designs often use adjustable jaws that are pined about a pivot point to grip the bolt head. This creates several problems. First, the pivot rotation about these pins cause the griping surface of the jaws to be angularly oriented from the faceted surfaces of the bolt head thus creating contact stress on the bolt head limiting torque transfer to a portion of the bolt head or deform the bolt head. In addition, adjustable pivoted arms are inherently weak since the torque that can be applied is limited by the strength of the pivot points. If greater strength is desired, the design requires up scaling the parts to where the tool may be so large that it will not be practical to use.
Other attempts to create a truly universal tool to solve these problems have also failed. For example, adaptable tool for gripping and torquing a variety of bolt heads of different sizes can be seen in Kleinsteuber, U.S. Pat. No. 1,155,662 which teaches a clamping device requiring the manual insertion of a stud into the jaws of the clamping device before beginning the torquing process. This tool requires screw tightening a stud into the head of the tool so that gripping surfaces can fit the bolt head to permit the transfer of torque. Likewise, Johansson U.S. Pat. No. 2,476,874 shows a grip chuck requiring manual twisting of a jamb nut about a collet in order to tighten the collet about the work piece before torquing.
Other tools designed provide for automatic sizing of the tool to a bolt head but fail to protect the grasping means from a torque induced bending mode. This problem can easily be understood when a pair of pliers is used to torque a bolt head from above the bolt head along the axis of rotation, from above. While the plier jaws can be sized to grasp the bolt head (albeit the jaw surface at an angle to the bolt head surface) the plier jaws will tend to bend and deform as torque is applied to the bolt head. Further, some tools also provide for imperfect contact or grip of the gripping means to the bolt head thereby failing to provide maximum torque should the bolt heads be worn or of imperfect size. For example, Van Dalen et al U.S. Pat. No. 3,373,639 and Strayer U.S. Pat. No. 2,599,026 teach tools which use resiliently deflectable jaws and resilient fingers, respectively, to grip a bolt head. These tools fail to address the bending mode problem of the grasping means when the tool torques the bolt.
As can be seen in other examples of prior art, applying torque in one rotational direction may not be the same as applying torque in the other rotational direction due to the lack of symmetry of the elements within the tool. For example, applying torque in the common drill chuck or lathe chuck will tend to increase grip upon the drill bit or object to be torqued in one rotational direction and tend to loosen the grip upon the drill bit or object to be torqued in the other rotational direction.